The purpose of this project is to extend the investigators' previously funded Peer Education in Pregnancy Study. The overall goal of the study is to examine the effect of peer education aimed at modification of the home environment on the development of asthma in children at risk for the disease. Secondary goals are to examine the effect of environmental, psychosocial, and nutritional risk factors on the development of asthma in the overall cohort. Specific aims of this proposal are to increase the total recruitment to 500 pregnant women and their unborn infants; increase the time of follow-up of the children to age 3-5 years; expand the exposure assessment to include dust measurements of endotoxins, pyrethroids, and organophosphates and urine measurements of pesticide metabolites; extend the psychosocial and nutritional assessments to include measurements of family function stress and diet during years 1-5; and expand immune assessments to include measurements of interleukins (IL-4, IL-13, and interferon-gamma) at one year of age. The effect of peer education on the development of asthma by age 3-5, as well as the effect of peer education on intermediary endpoints such as smoking, exposure to indoor allergens (cat, cockroach, mite, mouse, beta-glucan, and endotoxins), exposure to pesticides (pyrethroids and organophosphates), and immune function (IgE levels, skin testing for allergens, and cytokines) will be examined. Relationships of exposure to passive smoke, allergens, and pesticides, as well as measures of psychosocial function and nutrition, with the development of asthma and respiratory symptoms in the overall cohort will also be explored. Results of this study will assist in elucidating the etiologic pathway by which asthma develops early in life, as well as assist in the development of effective intervention programs.